Stainless steel turning data depends on the stainless family, workpiece condition, cutting edge and stability of the setup. The values below are Alleima’s starting recommendations for Sanmac 304/304L and 316/316L, paired with the insert geometry, grade and operation listed by the manufacturer. They are useful starting references for those materials, not universal settings for all stainless steels.

Turning Speeds and Feeds for Stainless Steel

Choose the matching material and operation

The table separates finishing/copy turning from medium machining and less-stable medium-to-rough work. The finishing entry uses an MF insert geometry and GC2015 grade at a starting feed of 0.15 mm/rev and speed of 250 m/min. For medium machining, Alleima lists MM geometry and GC2015 at 0.30 mm/rev and 225 m/min. It lists GC2025 at the same feed and 195 m/min when medium-to-rough machining under less stable conditions. Treat each pair as a linked recommendation, not as independently interchangeable feed and speed settings.

Sanmac is Alleima’s machinability-enhanced product family. The datasheet covers 304/304L and 316/316L variants; ordinary 304 or 316 from another producer may differ in composition, delivery condition and machinability. Ferritic, martensitic, duplex and precipitation-hardening stainless steels also have different cutting behavior. Identify the material from the purchase specification and verify whether the data source applies before using its starting values.

What the numbers mean

Cutting speed is the surface velocity at the tool edge, given here in metres per minute. Feed is the distance the tool advances during one workpiece revolution, in millimetres per revolution. On a lathe, spindle speed changes with diameter. The relationship is n = 1000Vc/(πD) for Vc in m/min and D in mm. A starting speed of 225 m/min at a 40 mm diameter corresponds to about 1,790 rpm. Check the chuck, workpiece balance, machine limit and constant-surface-speed settings before using that result.

Feed also affects the finish and the load on the insert. A stronger roughing geometry may tolerate a heavier feed than a finishing geometry, while a small nose radius or flexible setup can limit feed to control deflection and chatter. The values in the Alleima chart are starting values for particular geometry and grades, so confirm the insert maker’s current data for the exact catalog item you intend to use.

Account for work hardening and setup conditions

Austenitic stainless steels can work-harden if the tool rubs or dwells. Use a positive cutting action, maintain feed through the cut and avoid repeatedly rubbing a dull edge across the surface. Secure long bars, thin walls and slender features to resist vibration. Coolant delivery, chip evacuation and tool overhang also matter, especially in deep or interrupted cuts. Inspect the chip and cutting edge after the first passes; adjust gradually if you see built-up edge, notching, flank wear or chatter.

These recommendations do not cover every diameter, insert, operation or hardness. Temperature, surface condition, interrupted cuts and tool-life targets can move the suitable point within or beyond a supplier’s chart. Begin with the selected toolmaker’s current data, then qualify the cutting conditions on the production setup.

Before moving from a trial cut to production, compare the workpiece certificate with the exact Sanmac grade and delivery condition named in the source. Check that the cutting edge is sharp, the insert seat is clean and the toolholder is supported close to the work. Austenitic chips can be tough and stringy, so use chipbreaker geometry suited to the actual depth and feed, and confirm that guards and chip handling are appropriate. Record speed, feed, tool life and surface quality during a controlled run. These observations help distinguish a material or setup issue from an unsuitable starting value; they do not replace the tool supplier’s current application guidance.

Sources

Starting values are from Alleima’s Sanmac 304/304L technical datasheet, which also covers turning Sanmac 316/316L and labels the figures as starting values. Confirm material and insert details in the latest supplier documentation.